The present invention relates to endotracheal tubes used for conducting gases or vapors along the trachea, for example by an anesthesiologist, during the administration of anesthesia to patients undergoing surgery. In particular, the present invention relates to endotracheal tubes having means which enables the simultaneous administration of medication to both lungs of the patient during anesthesia. In addition, the endotracheal tubes according to the present invention are particularly useful for the paramedic in the field or the emergency room doctor, especially for the delivery of cardiac drugs.
Endotracheal tubes are generally used for anesthesia of a patient during surgery. Such endotracheal tubes may be introduced to the patient either orally or nasally. The endotracheal tube generally comprises a hollow tube made of a suitable plastic material, and which may be preferable pre-shaped so as to correspond to the patients pharynx and trachea. The endotracheal tube is inserted through the mouth or nose of the patient and extends along the patient's trachea.
It is often desirable to administer therapeutic drugs or agents directly to the lungs of the patient via an intubated endotracheal tube. Medications administered to the lungs in this manner are quickly taken up by the pulmonary (lung) vasculature and absorbed into the circulatory system.
Also, paramedics and emergency room doctors must often use endotracheal tubes to quickly intubate and apply mechanical ventilation to patients. It is often desirable to administer cardiac drugs through the intubated endotracheal tube directly to the lungs. Preferable, the cardiac drugs are distributed over as wide an area of the lungs as possible to optimally deliver the drugs to the circulatory system of the patient.
In general, drugs are delivered to a patient intravenously (IV). However, when venous access is difficult because of anatomy, trauma or disease, or in emergency situations, it is necessary to deliver drugs by another means, such as through an intubated endotracheal tube.
When the drugs or agents are to be delivered through an endotracheal tube, the generally accepted technique for administering such agents is to inject the agents into the proximal end of the endotracheal tube, and then "blowing" the drug down the tube into the lungs. However, there are several disadvantages to this method, including the need to interrupt ventilation during injection of the agent. In addition, it is difficult to measure the amount of agent actually delivered to the lungs, because the agent may be absorbed by secretions collected in the endotracheal tube, or may simply adhere to the walls of the endotracheal tube. Also, it is often desirable to atomize the agent during delivery, so as to provide better clinical results. Such atomization requires relatively high air flow, which can create other disadvantages. Finally, delivery through the main tube of the endotracheal tube makes it extremely difficult to administer the agent to both lungs of the patient, because the drug will generally flow through the distal end of the endotracheal tube and be administered to only one lung. It should be noted that a portion of the administered drug will often be expelled through the proximal end of the endotracheal tube upon exhalation by the patient.
Atomizing and delivery of the drug to both lungs of the patient is very important from a clinical standpoint. In particular, better clinical results can often be obtained by delivering smaller particles of the drug because the drug can then travel further into the small airways and alveolar surfaces. This allows the drug to spread out further and makes the kinetics approach that of IV delivery.
There have been several endotracheal tubes designed in an attempt to provide means of delivering drugs or agents through an endotracheal tube, which overcome the disadvantages noted above.
In particular, U.S. Pat. No. 4,584,998 to McGrail describes a multipurpose tracheal tube which may include up to three additional lumens formed within the wall of the main lumen. One of the additional lumens may be an insufflation lumen used to deliver humidified and atomized gasses to the patient. By providing an additional lumen, ventilation does not have to be discontinued, and metering of the agent delivered is simplified.
U.S. Pat. No. 4,669,463 to McConnell shows an endotracheal tube including a auxiliary lumen formed in the wall of the main lumen. The auxiliary lumen may be used to deliver liquid medicant to the distal end of the endotracheal tube.
U.S. Pat. No. 4,821,714 to Smelser is directed to an endotracheal tube having a primary lumen for delivery of ventilation gasses and a second lumen for administration of medication to the lungs of a patient. Smelser particularly describes an embodiment wherein the second lumen is branched and terminates at two outlets, one at the distal tip of the tube and the other along the exterior wall of the tube.
However, none of the prior art endotracheal tubes provide means for easily and effectively delivering medicant to the lungs of the patient, and more particularly to both lungs of the patient simultaneously.